Existing radio receivers use analog down-converters to convert a radio frequency (RF) signal to a signal with one or more lower intermediate frequencies (IF). The analog down-converters may have a heterodyne (one IF), super-heterodyne (multiple IFs), or zero IF architecture (the IF is actually 0 Hz). The analog down-converters suffer from analog impairments, such as analog variability, (e.g., component to component variability, temperature variability, voltage variability and variability due to aging) and inflexibility (i.e., an analog down-converter that is designed to operate efficiently for a specific frequency band, such as, 880-915 MHz, does not work well for other frequency bands, such as, 1920-1980 MHz).
Some of the analog down-converters are also affected by other problems (although not all architectures have all of the following listed problems): a variation over frequency (phase and amplitude), a quadrature imbalance (the inphase component leaking in to the quadrature component or vice versa), a gain imbalance, a DC offset, and a limited image rejection.
These impairments and problems currently make it difficult to design an analog down converter capable of processing radio frequency signals with frequencies spanning a wide frequency range (e.g., operating well both for the 880-915 MHz band and for 1920-1980 MHz band).
Commercially available digital down converters are not intended nor are capable of down converting a directly sampled radio frequency signal to baseband (0 Hz). It is generally assumed that the analog signals input to these digital down converters have already been brought to the intermediate frequency in a previous analog section of the signal processing chain.
Accordingly, it would be desirable to provide devices, systems and methods that avoid the afore-described problems and drawbacks.